LIPIDS METABOLISM.doc

7/27/2019 LIPIDS METABOLISM.doc

1/11

LIPIDS METABOLISM

1. The main enzyme for lipid digestion is:

a) Lipoprotein lipase

b) Pancreatic lipasec) Phospholipase C

d) Enteropeptidase

e) LCAT

2. The site of bicarbonate excretion:

a) Stomach

b) Duodenum

c) Jejunum

d) Ileum

e) Colon

3. Fatty acid oxidation is a significant source of energy in all of the following

except:

a)Liver

b) Kidney

c) Red blood cell

d) Heart

e) Skeletal muscle

4. Malonyl CoA:

a) Is the commited step in fatty acid synthesis

b) Level is decreased in the fasting state

c) Is a precursor of melanin

d) Is synthesized by pyruvate carboxylase

e) Is a precursor of cholesterol

5. During prolonged fasting:

a) B-oxidation of fatty acids is initiated

b) Glycogenesis is very active

c) Blood glucose level is maximum

d) Ketogenesis is maximal

e) Bicarbonate is high in the blood

6. The following are intermediates in cholesterol biosynthesis:

a)Prostacyclin and squaline

b) Lanosterol and squaline

c) Squalene and Malonyl CoA

d) Farnesyl pyrophosphate and thiamine pyrophosphate

e) Carbamoyl phosphate and mevalonate


2/11

7. Lipoprotein lipase:

a)Hydrolyses cholesteryl ester

b) Is present in the cytosol of adipocytes

c) Is active during starvation

d) Hydrolyses TAG in chylomicrons and VLDL

e) Is activated by glucagon

8. 3-HMG CoA is:

a) Intermediate in cholesterol synthesis

b) Intermediate in ketone body degradation

c) Precursor of fatty acids

d) Final product in ketogenesis

e) Three carbon compound

9. The contents of chylomicron include:

a)Apoprotein Ab) Apoprotein B-100

c) Apoprotein B-48

d) No cholesterol

e) Hormone sensitive lipase

10. In mammals, cholesterol serves as precursor of all of the following except:

a)Aldosterone

b) Corticosterone

c) Cholic acid

d) Lanosterol

e) Testosterone

11. Formation of ketone bodies:

a)Occurs in the cytosol of the liver

b) Increases during fasting

c) Starts from pyruvate

d) Requires lactate dehydrogenase

e) Is inhibited during fasting

12. Prostaglandins:

a)Are neurotransmitters

b) Are derivatives of cholesterolc) Are synthesized by cyclooxygenase from unsaturated fatty acids

d) Include propanol

e) Are found in adipose tissue

13. Concerning cholesterol biosynthesis:

a) Two squalene units are required

b) The rate of synthesis is controlled by the rate of production HMG-CoA

c) The liver is the only site for synthesis

d) NADH is required

e) Mevalonate is an intermediate


3/11

14. For transport across the inner mitochondrial membrane, long chain fatty

acids are attached to:

a) Coenzyme A

b) Acyl tansacylase

c) Phosphatidylethanolamine

d) Acyl transferasee) Carnitine

15. The activity of lipoprotein lipase is stimulated by:

a)Apo A

b) Apo B-48

c) Apo CII

d) Apo E

e) Apo B-100

16. The rate-limiting step in the conversion of cholesterol to bile acids:

a) Is side-chain oxidation b) 12-alpha-hydroxylation

c) 7-alpha-hydroxylation

d) 7-beta-hydroxylation

e) Conversion to coprostanol

17. Cholesterol is:

a) A source of energy

b) A precursor of vitamin K

c) Not found in lipoproteins

d) Precursor of steroid hormones

e) The same as the steroid nucleus

18. Fatty acid oxidation is a significant source of energy in all of the following

except:

a)Liver

b) Skeletal muscle

c) Kidney

d) Red blood cell

e) Heart

19. The rate-limiting enzyme in cholesterol biosynthesis is: a)Isopentyl pyrophosphate isomerase

b) Mevalonate kinase

c) 3-hydroxy 3-methyl glutamyl-CoA reductase

d) Dimethylallyl transferase

e) Squalene synthase

20. Triacylglycerol in chylomicron is mainly hydrolysed by:

a) Hormone-sensitive lipase

b) Lipoprotein lipase

c) Fatty acyl CoA transferase

d) Pancreatic lipasee) LCAT


4/11

21. The oxidation of the following is coupled to the production of NAD+H in the

cytosol:

a)Acetoacetic acid

b) Succinyl CoA

c) Malic acid

d) Phosphatidic acide) Malonyl CoA

#@22. The following compound is a COMMON intermediate in ketogenesis and

cholesterol synthesis:

a)Mevalonic acid

b) Acetoacetic acid

c) Succinyl CoA

d) 3HMG-CoA

e) Malonyl CoA

23. Concerning lipoproteins: a)VLDL is synthesized in the intestine

b) LDL contains endogenous cholesterol

c) Chylomicrons are synthesized in the liver

d) Lipoprotein lipase is a component of VLDL and chylomicron

e) The protein component decreases hydrophilicity

24. The following is correct on apolipoproteins:

a)Apo CII is coenzyme with HSL

b) Apo AI is coenzyme with choline acetyltransferase

c) Apo B100 interacts with LDL receptor

d) Apo CI is integral component of chylomicrons

e) Apo B48 is integral protein of HDL

25. Malonyl CoA:

a)Activates carnitine acyl transferase 1

b) Is increased due to glucagon stimulation

c) Is a precursor of melanin

d) Is synthesized by acetylCoA carboxylase

e) Is the immediate precursor of palmitate

26. Prostaglandins: a)Are endocrine hormones

b) Are synthesized from arachidic acid

c) Enhances smooth muscle contraction

d) Are involved in control of inflammation and blood pressure

e) Both C and D are correct


5/11

27. Ketone bodies:

a)Are synthesized in the mitochondria of the liver

b) Increase in the blood during starvation

c) Are good fuels for cardiac muscle

d) Increase in the blood in uncontrolled diabetes mellitus

e) All of the above are correct

28. During diabetic ketoacidosis there is a rise in:

a)Plasma free fatty acids

b) Plasma insulin level

c) Blood pH

d) Plasma alkali reserve

e) Bicarbonate

29. Denovo synthesis of cholesterol occurs mainly in:

a)Adipose tissue and muscles

b) Liver and intestinec) Endothelial cells and hepatocytes

d) Pancreas and bone marrow

e) All of the above

30. Lipoprotein lipase is:

a)Activated by insulin

b) Active during the fed state

c) Hydrolyses TAG

d) Activated in presence of Apo CII


31. Examples of sphinglipodoses include:

a)Gaucher's disease and Tay-Sacch's disease

b) Niemann-pick disease and von Gierke's disease

c) Andersen's disease and Krabbe's disease

d) Fabry's disease and rickets

e) Farber's disease and Refsum's disease

32. Acetyl CoA carboxylase:

a)Is activated by citrate

b) Converts acetyl CoA to pyruvatec) Converts acetyl CoA to malonyl CoA

d) Is a cytosolic enzyme

e) B is the only wrong statement

33. The following is correct:

a) The liver uses ketone bodies and fatty acids as major fuels

b) Skeletal muscles use glucose, fatty acids and ketone bodies as fuels

c) Red blood cells oxidize acetylCoA to carbon dioxide

d) Heart muscles are totally dependent on glucose as fuel

e) The brain uses glucose and ketone bodies as normal fuels


6/11

34. Fatty acid synthesis:

a) The committed step is catalyzed by fatty acid synthase

b) Steps shared between cytosol and mitochondria

c) Carnitine is needed for fatty acid transport to the mitochondria

d) Pyruvate carboxylase is a key enzyme

e) The liver and muscles are major sites

35. Ketone bodies:

a) Include acetoacetate and acetoacetyl CoA

b) Are produced in excess in the fed state

c) Are synthesized from pyruvate

d) Are produced by liver and kidney

e) Are preferred fuels by cardiac muscles

36. The contents of HDL do not include:

a) Apo A

b) Cholesterolc) Apoprotein B-48

d) Apo E

e) Apo C

37. Prostaglandins:

a) Are local hormones

b) Are derivatives of cholesterol

c) Are synthesized by lipooxygenase from unsaturated fatty acids

d) Include propanol

e) Are found in adipose tissue only

38. In cholesterol biosynthesis:

a) Prostacyclin and squalene are intermediates

b) 3-HMG CoA is a precursor

c) Rate is enhanced by epinephrine

d) Thiamin pyrophosphate is coenzyme with 3-HMG CoA reductase

e) All steps are reversible

39. Lipoprotein lipase:

a) Is cystolic enzyme

b) Is the same as HSLc) Is active during starvation

d) Requires biotin as coenzyme

e) Is activated by insulin

40. 3-HMG CoA is:

a) Intermediate in cholesterol degradation

b) Intermediate in ketone body synthesis

c) Precursor of fatty acids

d) Final product in ketogenesis

e) Three carbon compound


7/11

41. Triacylglycerol and glycogen:

a) Are storage form of energy in animals and plants

b) Are synthesized from glucose

c) Are transported between tissues as lipoprotein particles

d) Have the same energy yield on complete oxidation

e) Are mainly stored in the liver

42. The chylomicron:

a) Carries cholesterol from the intestine

b) Contains mainly TAG

c) Has apoprotein B-48

d) Has lower density than HDL


43. Citric acid:

a)Is produced in the mitochondria as a member of the TCA cycle

b) Is an allosteric activator of acetyl CoA carboxylasec) Is a source of cytoplasmic acetyl CoA

d) Is cleaved in the cytosol by an ATP-dependent lyase

e) All of the above

44. Inherited disorders of B-oxidation:

a) Include Refsum's disease which is due to absence of peroxisomes

b) Acyl CoA dehydrogenase deficiency causes hyperglycemia

c) Include dicarboxylic aciduria

d) Causes hemolytic anemia

e) Includes McArdle disease

45. Acetyl CoA Carboxylase:

a)Catalyzes committed step in glycogen synthesis

b) Converts acetyl CoA to pyruvate

c) Converts acetyl CoA to malonyl CoA

d) Is a mitochondrial enzyme

e) Needs folate as co-enzyme

46. Malonyl CoA:

a) Is activated form of acetyl CoA

b) Is increased during glucagons stimulationc) Inhibits carnitine palmitoyl transferase-1

d) Synthesis does not require biotin as cofactor

e) Can be converted to glucose in the liver

47. Lipolysis in adipose tissue:

a) Is catalyzed by lipoprotein lipase

b) Is enhanced in the fed state

c) Produces fatty acid and glycerol

d) Is enhanced by insulin secretion

e) Produces ketone bodies


8/11

48. Ketone bodies:

a) Formation occurs in the mitochondria of hepatocytes

b) Levels in blood increase with prolonged starvation

c) Are increased in blood patients with uncontrolled diabetes mellitus type-1

d) Are prefentially used by heart muscle

e) All of the above is correct

49. Prostaglandins:

a) Primarily synthesized from eicosanoic acids

b) Closely related to thromboxanes

c) Potent smooth muscle contractor

d) Local hormone


50. In lipoproteins:

a) VLDL is the major carrier of dietary triglycerides

b) LDL contains endogeneous cholesterolc) Chylomicrons are synthesized in the liver

d) Hormone-sensitive lipase is a component of HDL

e) The protein component increases the hydrophobicity

51. Gallstone blocking the common bile duct will result in the impaired intestinal

absorption of all the following except:

a)Retinol

b) Cholecalciferol

c) Cholesterol

d) Diacylglycerol

e) Folic Acid

52. Beta-oxidation of a fatty acid:

a)Produces ATP at substrate level

b) Involves two steps of reduction of fatty acid

c) Has a preference for fatty acids shorter than 12 carbons

d)Requires NAD+

e) Is a cystosolic pathway

53. Glycerol-3-phosphate in adipose tissue arises primarily from:

a)Reduction of dihydroxyacetone phosphate b) Hydrolysis of phosphatidic acid

c) Phosphorylation of glycerol by glycerol kinase

d) Selective uptake from blood

e) Reduction of glyceraldehydes-3-phosphate

54. Cholesterol is:

a)A normal membrane constituent of plant cells

b) Converted to cholic acid by intestinal bacteria

c) Important source of energy

d) Parent molecule for cholecalciferol

e) Synthesized in the liver mitochondria


9/11

55. Derivatives of cholesterol include all of the following except:

a)Cholecalciferol

b) Cortisol

c) Retinol

d) Chenodeoxycholate

e) Aldosterone

56. The activity of acetylCoA carboxylase is enhanced:

a) Dephosphorylation

b) Insulin

c) Citrate

d) Esterification of fatty acylCoA


57. In lipogenesis and beta oxidation:

a) Carnitine palmitoyl transferase I is enhanced by malonyl CoA

b) The two pathways are mitochondrialc) High level of cytosolic fatty AcylCoA enhances lipogenesis

d) Insulin enhances malonyl CoA synthesis which indirectly inhibits beta

oxidation

e) NADPH is needed

58. Conversion of glucose to TAG in the liver requires all of the following except:

a) Acetyl CoA carboxylase

b) Fatty acid synthase

c) Pyruvate dehydrogenase

d) Glucose 6 phosphatase

e) Glycerol 3 phosphate dehydrogenase

59. All of the following are synthesized in the liver in the fed state except:

a) VLDL

b) Glucose

c) LDL

d) PRPP

e) Cholesterol

60. During fasting the following pathways are active in the liver except:

a) Glycogenolysis b) Glycolysis

c) Ketogenesis

d) Beta oxidation

e) Gluconeogenesis

61. Concerning cooperation between the liver and adipose tissue:

a) TAG is synthesized in the adipose tissue and transported to the liver

b) Ketone bodies are synthesized by the liver and consumed in adipose tissue

c) LDL is released from adipose tissue and oxidized in the liver

d) VLDL is synthesized in the liver and converted to HDL in adipose tissue

e) HDL is synthesized in the liver and degraded in adipose tissue


10/11

62. The main sources of energy in skeletal muscle during vigorous exercise are:

a) Fatty acids and creatine phosphate

b) Anaerobic oxidation of glucose and creatine phosphate

c) Blood glucose and ketone bodies

d) Fatty acids and glycerol


63. In the cardiac muscle:

a) Glycogen is the main energy reserve

b) Ketone bodies are preferred over glucose for energy production

c) Anaerobic glycolysis is vital

d) Fatty acids are not used in the fed state

e) None of the above is correct

64. In the brain:

a) Most of the energy is used for generation of nerve impulses

b) Glucose is a sole fuel under normal conditionsc) There is a high turnover of biomolecules

d) Ketone bodies can be utilized


65. Insulin promotes fat storage in adipose tissue cells by:

a) Inhibition of HSL

b) Stimulation of lipoprotein lipase

c) Stimulation of glycolysis

d) Enhancing glucose uptake


66. Ketone bodies are present in high levels in the blood when:

a) Hepatic glycogen levels are high

b) Fat is being actively synthesized

c) Protein synthesis in muscle is elevated

d) Blood glucose is high

e) Fatty acid oxidation is high in the liver

67. Malonyl-CoA:

a)Is produced from citrate

b) Is increased during glucagons stimulationc) Inhibits carnitine palmitoyl transferase-1

d) Synthesis require folate as a coenzyme

e) Is converted to glucose in the liver

68. The following is correct about chylomicron:

a) It is formed in the intestinal mucosal cells

b) It contains the apoprotein B48

c) It is carried from the intestinal mucosa to the circulation through lymphatic

vessels

d) The major load is dietary triacylglycerol



11/11

69. The major carrier of cholesterol from the liver to the tissues is:

a) HDL

b) IDL

c) LDL

d) VLDL

e) HDL2

70. The HDL play a major role in:

a) Transport of phospholipids to the tissues

b) Synthesis of triacylglycerol

c) Delivary of apoprotein B100 to VLDL

d) Transport of cholesterol from the tissues to the liver

e) Storage of apoproteins

71. Triacylglycerol is mainly transported between tissues in:

a)VLDL and chylomicron

b) LDL and HDLc) Chylomicron and IDL

d) The free form

e) HDL and VLDL

72. The following is correct about lipoproteins:

a)VLDL is the precursor of IDL

b) IDL is the precursor of LDL

c) LDL receptor binds apoB100

d) LDL receptors are defective in familial hypercholesterolemia


73. Cholesterol is:

a)Supplied to tissues through LDL receptors

b) Taken from tissues by LCAT of HDL

c) Increased in the blood of patient with a defective LDL Receptor

d) Stored in tissues by the action of ACAT


74. Eicosanoids:

a)Are neurotransmitters

b) Are derivatives of cholesterolc) Are synthesized by cyclooxygenase from unsaturated fatty acids

d) Include Prostaglandins

e) Are found in adipose tissue only

Documents

LIPIDS METABOLISM.doc